The present invention relates to a discrete strip of paperboard or card material from which to form a rigid container consisting in a box with a hinged lid, notably for wrapping cigarettes, and to the container obtainable by folding such a strip of material.
Containers of the type in question, recognizable in particular as `flip-top` cigarette packets, are folded from die-cut cardboard strips of essentially rectangular shape which appear symmetrical in relation to a longitudinal axis and are divided up into a number of sections by creases and cuts.
The flat strip comprises a first section, destined ultimately to form the bottom of the box, and two further sections aligned in the direction of the longitudinal axis, one on either side of the first, constituting the front and rear faces of the box; two flaps are associated with each face, projecting one on either flank of the strip in a direction transverse to its longitudinal axis and disposed in parallel alignment with the longitudinal axis, which are folded into overlapping contact, those of the front face outermost and those of the rear face innermost, to form the sides of the box.
The strip comprises a further portion from which to fashion the lid; this portion comprises a section designed to form the top of the packet, which is located between two sections destined ultimately to provide the rear and front of the lid, the rear of the lid being separated from the rear face of the box by a hinge crease, and the front of the lid destined to register with the top edge of the front face of the box.
Two pairs of flaps project on either flank from the front and rear of the lid, respectively; these are designed ultimately to overlap, those of the front outermost and those of the rear innermost, thereby forming the sides of the lid.
The flat strip is completed by two pairs of tongues extending respectively from the inner side flaps of the box and the inner side flaps of the lid, which provide four reinforcements for the four relative corners of the packet, and a further tongue for reinforcement of the lid, which extends from the projecting transverse edge of the lid and is folded in against the relative inside surface.
The strip is folded by mechanical means operating in conjunction with glueing devices, by which the inner and outer flaps of the box and the lid are stuck together, and the reinforcing tongues folded in place at the top and the bottom corners of the packet, and against the inside surface of the front of the lid, respectively.
When packaging cigarettes, and indeed when wrapping other commodities, the product is protected further against the surrounding environment by enveloping the packet in a wrapping of heat-sealable film, for example cellophane.
A sheet of such film is first wrapped around the packet in tubular fashion, covering the front, rear and sides, and joined and sealed down one side. Thereafter, the ends of the tube are folded down over one another against the top and bottom of the box, and heat-sealed to envelop the packaged item completely. This operation is effected by means of heat-sealing devices that compact the overlapping thicknesses of film together, exploiting the sides of the packet, then the top and bottom, as a breast against which to apply the necessary pressure.
It has been discovered that errors occurring in the course of the packet's construction, for example due to incorrect execution of the creases or cuts during preparation of the strip of paper material, or to incorrect positioning of the inner and outer flaps of the box and lid one in relation to the other when folding and glueing, or again, due to incorrect assembly of the various sections of the packet, can give rise to imperfections; the top and bottom may project beyond the sides of the box and lid, or the horizontal edges of the side flaps may project respectively above and below the top and bottom of the packet; at all events, the end-result is that the defective side, top or bottom surface of the packet cannot be exploited successfully for heat-sealing purposes as mentioned above.
The result of such a shortcoming is to inhibit an accurate heat-seal of those parts of the cellophane which cover the side, top and bottom of the packet, and given that this condition will be detected by the conventional monitoring devices with which the cellophane wrapping units of cigarette production lines are normally equipped, the substandard pack of cigarettes may well be rejected altogether in consequence.
The object of the present invention is to overcome the drawbacks thus outlined through the provision of a discrete strip of paper material from which it will be possible to obtain flip-top packets that are free of defects pertinent to the prior art as mentioned above.